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arXiv 1102.5130cond-mat.supr-con
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电流偏置薄膜超导窄条中的涡致耗散

Vortex-induced dissipation in narrow current-biased thin-film superconducting strips

L. N. Bulaevskii, M. J. Graf, C. D. Batista, V. G. Kogan

摘要:

垂直于偏置电流从一个边缘到另一个边缘穿过薄膜超导带的涡旋是厚度为d的薄膜的主要耗散机制,厚度为d的薄膜的相干长度为XI,宽度为w的薄膜的相干长度为λ>> w >> XI。在高偏置电流下,I* < I < Ic,由单个涡旋的交叉释放的热量足以在条带上产生带状正常状态区域,从而产生可检测的电压脉冲。这里Ic是一个单一的涡流交叉的能量势垒消失的临界电流。该带沿着涡流路径形成,并导致整个带过渡到正常状态。我们估计I* 大约为Ic/3。此外,我们认为,这种“热”的涡旋交叉点的起源暗计数的光子探测器,在该制度的亚稳超导电流I* 和IC之间的操作。我们估计的速度的旋涡交叉点,并比较它与最近的实验数据的暗计数。对于低于I* 的电流,即,在稳定的超导但电阻制度,我们估计的幅度和持续时间的电压脉冲引起的一个单一的涡旋交叉。

英文摘要:

A vortex crossing a thin-film superconducting strip from one edge to the other, perpendicular to the bias current, is the dominant mechanism of dissipation for films of thickness d on the order of the coherence length XI; and of width w much narrower than the Pearl length LAMBDA >> w >> XI. At high bias currents, I* < I < Ic, the heat released by the crossing of a single vortex suffices to create a belt-like normal-state region across the strip, resulting in a detectable voltage pulse. Here Ic is the critical current at which the energy barrier vanishes for a single vortex crossing. The belt forms along the vortex path and causes a transition of the entire strip into the normal state. We estimate I* to be roughly Ic/3. Further, we argue that such "hot" vortex crossings are the origin of dark counts in photon detectors, which operate in the regime of metastable superconductivity at currents between I* and Ic. We estimate the rate of vortex crossings and compare it with recent experimental data for dark counts. For currents below I*, i.e., in the stable superconducting but resistive regime, we estimate the amplitude and duration of voltage pulses induced by a single vortex crossing.

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